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Core Memory

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@rt:
Hi Guys :)

I’m making a core memory, and have built this pulse detector circuit which should output a logic pulse
for a positive or negative going input pulse. When I powered it up, the output pin always reads high by a micro controller.

Now looking closer at it, it looks like the output is tied high with the nearest 10K resistor,
and either transistor can only short the output to ground.
Should it be expected behaviour that the output is inverted, and will only output low when it receives a pulse?
Cheers, Art.

matseng:
Yes, it will pull the output down to ground very briefly at every falling and leading of the pulses at the input.  My guess is that you'll need to either extend the output pulse or let it trigger a flipflop in order to be able to catch them with the microcontroller.

@rt:
Thanks, as I expected, but appreciate confirmation.

Apparently the pulse is long enough to catch. I’m running a pic at 24MHz, so 6M instructions per second.
I cannot assert this from experience, but judging from the two people with online blogs having done it,
the pulse arrives at a reliable (repeatable) time after the current to the address lines is switched on.
You don’t want to be looking for a pulse outside of a small time window, because the desired pulse is surrounded by switching noise.

@rt:
Ok, I have had success :) If anyone wants cloud storage, it’s $1K per bit, per annum.
I only have 64 bits, so you’ll understand they are at a premium.



WN1X:

--- Quote from: @rt on August 12, 2015, 04:25:59 pm ---Ok, I have had success :) If anyone wants cloud storage, it’s $1K per bit, per annum.
I only have 64 bits, so you’ll understand they are at a premium.

--- End quote ---

That is very cool! Now you need to build a drum storage device  :o

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